Predictions for the Big Apple haven’t been so great lately, at least as far as climate is concerned. News from a week ago was that heat-related deaths are predicted to rise by 20% by the 2020s and by nearly 100% by the end of the century. Scientific American summarizes the work published this month in the journal, Nature Climate Change, and includes this quote from one of the authors:

“This serves as a reminder that heat events are one of the greatest hazards faced by urban populations around the globe,” said coauthor Radley Horton, a climate scientist at the Earth Institute’s Center for Climate Systems Research.

The record 2010 heat wave that hit Russia, killing some 55,000 people, and the 2003 one in Europe that killed 70,000 are potent examples of the devastation that extreme heat can cause, Horton added.

This week, Scientific American published another warning for NYC and the rest of the East Coast. The climate threat in this case is flooding – the possibility of Hurricane Sandy-like flooding every two years by century’s end! Salon summarizes the SA behind-the-paywall story here. A few planning details:

Municipalities rarely plan for anything greater than the so-called one-in-100-year storm—which means that the chances of such a storm hitting during any given year is one in 100. Sandy was a one-in-500-year storm. If sea level rises by five feet, the chance in any year of a storm bringing a three-foot surge to New York City will increase to as high as one in three or even one in two, according to various projections. The 100-year-height for a storm in the year 2000 would be reached by a two-year storm in 2100.

The Adventures of Tom Sawyer was the family read-aloud book this past spring. I found myself especially drawn to Twain’s description of the Mississippi River, a reminder of how much of an impact the Big Muddy had on my own childhood as I grew up along its banks. Naturally, I watched the new reports in May as my hometown flooded, and I wondered if the many miles of levees could possibly hold. The system put in place by the U.S. Army Corps of Engineers largely did its job, but the river still exacted a price, eating away at the banks and attempting to carve new channels (i.e., doing what rivers do in flood events). A report in the Memphis Commercial Appeal details the costs of “bank failures” from the big flood. With federal budget cutting fever rampant in D.C., you have to wonder about how many federal dollars will be directed toward the repairs.

Corps officials estimate it will cost $222.5 million to undo the damage inflicted by the river as it tried to create new channels during the flood. If the repairs aren’t completed before the next big flood, the Mississippi could complete the course changes it began this year.

That $222.5 million sum is in addition to the projected $327.7 million it will take to fix flood-damaged levees, the $157.4 million worth of flood-related dredging needed and the estimated $70.6 million required to restore spillways and similar structures.

To pay for those and other damages, the U.S. House approved $1 billion in emergency appropriations for the corps in the energy and water bill. But the Senate has yet to approve any funds.

A retired Army Corps hydraulics engineer, Larry Banks is quoted in the article:

“We don’t control the river. The river is the control,” Banks said. “The works of the corps can tickle it a little bit and keep it manageable.”

One of the bank failures, .5 mi wide and 1 mi deep into Presidents Island near Memphis. Photo by International Port of Memphis.

What do you do when historical data is no longer useful for predicting the future? Climate change is making the already-difficult proposition of predicting environmental phenomena even harder. Consider societal efforts to manage the flood system. The concept of a 100-year flood is based on the idea that history is useful indicator of future states and “most likely” scenarios. A 2010 paper by Gersonius et al.* tackles the question of how we might begin to plan for shifts in flooding regimes by using adaptive management strategies. This paper is at the leading edge of climate adaptation design research, and there is a need for much more.

Gersonius et al. contrast the traditional approach with an adaptive approach. They say that traditional approaches are based on the assumption “that it is possible to define a singular optimum adaptation strategy according to the ‘most likely’ or average future projection” (p.15). Big investments of public dollars are common with the traditional approach – essentially a large bet on the promise of a singular optimum strategy (one-off interventions). The paper’s authors argue for an adaptively resilient approach instead, an approach better suited to the uncertainties of climate change.

Rather than taking a traditional approach, responsible climate adaptation requires an alternative approach that attempts to assess and manage the resiliency of the flooding system for long-term future change. The aim of this approach is to keep the system within a configuration of states that give at least acceptable functioning despite the occurrence of possible changes (Walker et al. 2002**). This means that the approach acknowledges that projections are ‘always wrong’ and that it is necessary to plan for a range of possible future conditions.

The authors’ modeling results suggest that adaptation decisions that include LEARNING about future climate parameters could reduce overall costs between 5 and 17% over a single high risk traditional, or “robust,” intervention. The figure below illustrates the concept.